Warnick C.C. Hydropower engineering

Подождите немного. Документ загружается.

Hydrologic Analysis for Hydropower

Chap. 5

Location of

representative

unregulated flo

Flow desired at this point

Physiographic Layout

Reservoir

Obtain from entity

operating reservoir

(location at A).

2:Determine average

annual runoff from

ungaged tributary

Cornpure sequential

Planimeter N.A.P. maps

and estimate

coefficlent

of runoff. See Eq.(5-1)

(location

considering

area

M).

flow from ungaged

rributary area

See Figure

5-7.

This

simple sequential

addition of calculated

ungaged tributary area

inflow from ungaged area

plus

observed reservoir

(outflow.

flgw analysis

Figure

5.6

Di:~gram

showing

neth hod

for determining flow duration

regulated

flow

combincd with ungaged inflow.

.omla1 annual precipitation input value by the runoff coefficient gives the average

nnual runoff fro111 the area

Mathematically, this is indicated as follows:

FAnl&

(5.3)

:here

Q,,,,

average

annual runoff volume per year froni area

average

a~lnual

precipitation,

depth units

Flow

Duration Analysis

area of the contributing drainage, square-length units

annual runoff coefficient, a decimal fraction of amount of precipita-

tion that runs off the drainage.

sequence of flows coming off area

must be computed. The time incre-

ments or periods must correspond to the records of

discharge available from the

reservoir operation. First a flow record at station

nut be obtained and studied.

The record at

is assumed to have the same time distribution of flow as the runoff

coming off area

(refer to Fig.

5.6).

An incremental fraction of flow,

ai,

for each

increment of time in the total desired time period must be obtained for the repre-

sentative gage

Figures

5.6

and

5.7

give flow diagrams for a step-by-step process

to calculate the sequential inflow from the ungaged area labeled

12;1

in Fig.

5.6.

Once

the sequential flows have been computed it is a simple procedure to add,

sequen-

Distribution of flow at gage

representative must be representative of

stream gage

hat can be expzcred from

station

ungaged tributary area

a, flow volume for

(5-31

period

divided by

total volume for entire

period

to n

where a,

Incremental flow

fraction for a particular

period

Compute incremental

flow fraction for

representative gage

at station

will be sequentially each

number from

to n

number of time periods

in entire record of flows

at station

(months, days)

qsMl

a, QMmlt

(5-4)

Compute ungaged

tributary area where

inflow from ungaged

tributary area M fo

period

(CFS or m Isec)

Roceed to sum

with regulated

outflow from reservoir

average annual

runoff in volume

units for area

number of years

in entire period

between

and

Ian

time units for

each period

Figure

5.7

Flow diagram for computing sequential flow magnitude from ungaged

tributary

area.

Hydrologic Analysis for Hydropou~er Chap.

Outllo~ from uprtream reservoirs

Flows in

CFS

Js~i

Feb

Mar

Apr

May

Jun

Ju!

Aug

Sep Oct

Dec

100

200 250 250

200

60 55

Compute average annual runof! from tributary

area

using

NAP

maps or

other methods

Average

runofl from tr~butary area

43.000

CFS-days

Choose represenlative gage

Flow,

CFS

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nw Oec

25 20 40

100 300 75 60 50 40 30

Runoff cfrdays = flow

number of days in month

e.g Flow

(Jan1 =

cfs

days

775

cfjdays

Jan Feb

Mar

Apr

May

Jun

Jul

kug

Sep

Oct

Nov

Dec

775 560

1240

1400 3100

90LX 2325

1860

1500

1240 900

775

Tatal runoff for period of record =

R.O.,

I.,

total,monfhs

record

775

%0+ 1240

1500

3100+ 9000

2325

1860+ 1500

1240

900

775-

24,775cfs-day

Compute flow fraction for representative gage

(R.O.

for month),

MFF,

Total runoff for period

month

eg.

MFF (Jan)

775

0.0313

24775

cfs-day

Jan Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct Nov

0.0313

0.0226

0.0501 0.0565

0.1250 0.3633 0.0938

0.0751

0.0605

0.0501 0.0363 0.0313

Compute tributary inflows

Inflow

Fract,

ava annual R.O. from trib. area

years in record

Days in month,

e.g Inflow

(Jan1 =

0'0313

43000

43.4

Jan Feb

Mar Apr

May

Jun

Jul

Aug

Sep Oct

Nov Oec

43.3

34.7

69.5 81.0

173.4

520.7 130.1

104.2

86.7 69.5 52.0

43.4

Computer flows at desired point

Flow, = outflow, from reservoir

tributary inflow

e.g flow (Jan)

cfs

43.4

cfs =

93.4

CIS

Jan

Feb

Mar

Apr

May

Jun

Jul Aug

Sep Oct

Dec

93.4

79.7

149.5

181.0 373.4

770.7 380.1

304.2

156.7 134.5

112.0 98.4

Figurc

5.8

Numeric example of calculations for

regulated

flow combined with

ungaged area inflow.

Energy and Power Anaiysis Using A Flow Duration Approach

tially, the flow from the ungaged tributary area

the regulated flows. Figure

5.8

a numerical example using the technique described above.

The increment of time is

a month,

wit11 the regular ~~uniber of days in each month being appropriately

accounted for in the calculations. Care should always be taken that the correct

volume and time units are used in these calculations. With the runoff or flow value

for

each increment of time

through

generated, it is then possible to generate a

flow duration curve for

the point

followi~ig either the rank-ordered technique

the class-interval technique.

problem using this approach with real data has been

included at the end of the chapter to make this more meaningful. More detail on

this procedure can be found in

Heitz (1981).

Deterministic and Stochastic Flow Methods

With appropriate data on precipitation, antecedent conditions, soil conditions,

and terrain characteristics, it is possible to generate flow data for use in hydropower

analyses.

Numerous deterministic models of varying sophistication are now available

to make simulations of hydrologic runoff. Two valuable references are the

SSAR

model (U.S. k~ny Corps of Engineers, 1972) and the Stanford Watershed Model

(Crawford and Linsley,

1966)

and its various improvements, known as the Hydro-

comp Simulation Program.

Stochastic models approach the time distribution of flow as statistical and

treat the occurrences as probability distributions. With good historical data it is

possible to generate a time series of flow data of any length.

excellent reference

on this is the work of

Haan (1977).

The questions to be asked regarding the use of hydrologic stream flow simula-

tion models are: (1) Do the basic historical and physical data on the. river under

study justify the use of models?

(2)

Do the time and cost permit their use?

ENERGY AND POWER ANALYSIS USING

FLOW

DURATION APPROACH

In processing regulated and unregulated flow data, it is important to recognize that

in the power equation,

Eq.

(3.8),

flow is the primary limiting factor. When a run-of-

river type of power study is done and a flow duration analysis is used, the capacity

or size of hydropower units determines the

~naximum amount of water that will go

through the unit or units. This is dictated by the nominal runner diameter and the

accompanying outlet area and draft tube.

flow duration curve is used to explain

discharge capacity,

Q,,

as labeled in Fig. 5.9. This

is the discharge at full gate

opening of the runner under design head. Even though to the left of that point on

the duration curve the stream discharge is greater, it is not possible to pass the

higher discharges through the plant. If the reservoir or

pondage is full, water must

be bypassed by a spillway.

To the right of the runner discharge capacity point, Q,, it should be noted

that all the water that can go through the turbine is the

mount flowing in the

Hydrologic Analysis for Hydropower

Chap.

20 40 60

100

Percent of time flow is equal to or greeter than

Figure

5.9

Flow-duration curve sl~owing discharge capacity value.

Percent of

time

power is equal to or exceeded

Figure

5.10

Power duration curve.

Energy and Power Analysis Using A Flow Duration Approach

stream at the particular percent of time point. This shows that full-rated power

production will not be produced. With

pondage it is possible to alter this for short

periods of

the, but the total amount of energy output cannot be increased.

hydraulic head and the expected losses in the penstock are known, it is

possible to generate a power duration curve from the flow duration curve. Figure

5.10

gives an example of a power duration curve. The

value is the full-gate dis-

charge value of power and comes from multiplying

Q,,

discharge capacity value, by

the simultaneous value of head, the estimated turbine efficiency, and the appropri-

ate conversion constants [see

Eq.

(3.9)].

Energy production for

year or a time

period is the product of the power ordinate and time and is thus the area under the

power duration curve multiplied by an appropriate conversion

factor. It is conven-

tional to use the unit of energy measurement as the kilowatt-hour,

kwh. An exam-

ple tabulation of how the calculations might be made is shown in Table

5.2.

should be noted that to the left of the power capacity point the power tends to

decrease. This is due to the fact that net head available is decreasing due to a rising

tailwater caused by the higher flows that are occurring during that time interval or

exceedance period. The calculations in Table

5.2

reflect this situation.

TABLE

5.2

Computational Table for Power Capacity

Duration

(%)

0 10 15 20 3 0 40

River

8000 3400 2700 2150 1550 1150

discharge

(it 3/sec)

Head (it)

80.0 81.6 83.0 83.5 83.5 83.5

Plant

2662 2689 2700 2150 1550 1150

discharge

(ft3/sec)

Efficiency

0.88

0.89

0.90

0.90 0.88

0.87

Power

(kW)

15,855

16,704 16,920

13,588 9636

7068

Duration

(8)

50 60 7 0 80 90 100

River

850 650 500 420 4 00 100

discharge

(ft3/sec)

Head (it)

83.5

83.5 83.5

83.5

Plant

850 650

5 00 420

00 100

discharge

(ft3/sec)

Efficiency

0.87 0.83

0.75

0.70

0.60 0.50

Power

(kW)

5 224

381

2649 2077

1695 353

Hydrologic Analysis for Hydropower Chap.

Figure

5.11

Tabular

form

and

flow

diagram

for

sequential

flow

analysis.

Year

Month

data, can

monthly, weekly, daily, or hourly

Other Hydrologic Considerations

SEQUENTIAL-FLOW METHODS

Inflow to reservoir: Obtain from hydrologic analysis

Inflow

flows to be in true time sequence may need adjustment

CFS

for evaporation loss

End-of-month

In some cases it is wise to do a true time analysis of the hydrologic portion of

hydropower study. In cases n,here flow regulation and storage operatior1 are im-

portant, it is necessary to resort to a tabular operations study.

This is often referred

to as a

sequential-flow

study.

Such a study entails

the same problem found in a flow duration study, gettin;

discharge data at the desired location. This means getting records of flow into the

reservoir and the use of appropriate llydraulic head, area-capacity curves, and opera-

tional decisions on how

the water will be released through the turbines or bypassed

over a spillway. Losses such as evaporation and leakage may need to be taken

ulto

account. Figure

5.11

presents a typical tabular form for such a study with an ex-

planatory flow diagram to show how such a sequential-flow study can be organized

OTHER HYDROLOGIC CONSIDERATIONS

Hydrologic infornlation is also needed for developing tailwater curves, area-capacity

curves for reservoirs, rule curves for operating reservoirs, determination of seasonal

losses

from reservoirs due to evaporation, and flood analysis for spillways. Brie!

discussions on each

ol these topics are presented together with definitive reference:

for making studies of this type related to hydropower studies.

Tailwater Relationships

As releases of water over spillways and any other releases into the streani

immediately below a hydropower plant are made, the

tailwatsr elevation below t!~

outlet to the turbines will fluctuate. Therefore, it is important to develop a tailwater

elevation versus river discharge curve over the complete range of flow that is to bc

expected. Figure

5.12

is a typical example of a tailwater rating curve. Preparin:

such a curve requires an adequate contour map of the channel area and an esti~nat~

of velocity in the channel at various stages of flow. Information on normal tail

water, maximum tailwater, and minimum tailwater elevations is necessary

to deter

mine design head and to determine the appropriate turbine setting. Estimates

stream channel velocity can be made using slope-area calculations that involve thc

conventional Manning's open-channel-flow equation.

Area-Capacity Curves

Most hydropower developments involve an impoundment behind

dam.

the water in storage in the impoundment is released the headwater elevation changes

and this will influence the design of the plant and the pattern of operation. There-

fore, it is necessary to have a storage or

pondage volunle versus ilnpoundmcnt

surface elevation curve or table. At the same time there is need to know water

Hydrologic

Analysis

for Hydropower

Chap.

Discharge

thousands of

C.F.S.

Figure

5.1

Typical tailwater rating curve.'

iurface area versus impoundment elevation. This information can be obtained by

~lanimetering a contour map of the reservoir area a11d making necessary water

{olume calculations and water surface area determinations. The two curves are

ypically combined into what is termed an srea-capacity curve. Figure

5.13

is a

ypical area-capacity curve for a hydropower development.

Reservoir

Rule

Curves

IVhen releases from reservoirs are made, the schedule of releases is often

lictated by considerations other than just meeting the flow demands for power

Area

Figure

5.13

Typical ares<apacity curves.

Ac,

lo6

Other Hydrologic Considerations 77

100

--I--

Top of sediment reserve

.-----

700

600

500

400-

300

Mi-

Top of flood control space

Zone

a;d[crejtionj;ce,

1 1

Dead

storage

Jan

Feb

Mar

Apr

May

Jun Jul

Aug

Sep Oct

NOV

Dec

Time of year

Figure

5.14

Example reservoir operation rule curves.

SOURCE:

U.S.

Army

Corps

of Engineers.

Top of conservation

space

production. The needs for municipal water supply, for flood control, and for down-

stream irrigation use dictate certain restraints. The restraints are conventionally

taken care of by developing reservoir operation rule curves that can guide operating

personnel in making necessary changes in -reservoir water releases. Figure

5.14

shows example reservoir operation rule curves.

To be effective, rule curves often require the use of rather careful and exten-

sive reservoir operation studies

using historical flow data and estimates of demands

for water that are likely to occur in the future. The

techniques for study of reservoir

management and

optimization of reservoir use are many, varied, and presently re-

quire a great amount of digital computer time. A report by Chankong and Meredith

(1979)

gives a modern treatment of the formulation and procedures that can be

used. This report contains an

exhaustive bibliography on the subject of reservoir

operation studies as related to rule making.

good practical treatment has been

given by the

U.S.

Army Corps of Engineers

977).

Topofb~fierssace

zone

FIOO~

control

-.I----

Zone

Conservation

Hydrologic

Analysis

for Hydropower

Chap.

Evaporation Loss Evaluation

Where there is an impoundment involved in a hydropower

developnlent there

necd to asscss the effect of evaporation loss from the reservoir surface. This loss

iii

warmer areas can aniount to as much as

ft. of water evaporated from a reservoir

it1

a suninier season. The National Weather Service has developed regional evapora-

tion

rnaps that give lincs showing the evaporation rates in various regions of the

country. Similarly,

there are f:equently records of evaporation on at least a monthly

basis at nearby reservoirs.

In some cases it may be necessary to use empirical equa-

tions to obtain information on evaporation. The equation requires various measured

data such as radiation,

dewpoint readings. air and water temperatures, and wind

speed to calculate the evaporation rates. Good treatments of techniques for calcu-

lating evaporation from meteorological measurements are those of

Veiluneyer

(1964) and Viessman, Harbaugh, and Knapp (1972).

Spilll~ay Design Flood Analysis

Many hydropower developments require a dam or a diversion that blocks the

ilorn~al river flow. This then requires that provisions be made for passing flood

flows. Spillway design flood analysis treats a unique type of hydrology that

con-

ccrrls the occurrence of rare events of extreme flooding. Flood frequency analysis

has become a well-developed technique, and the U.S. Water Resources Council

977)

has

developed

a standardized procedure for making flood frequency analyses.

is custorna~y on larger dams and dams where failure might cause a major disaster

to design the spillway to pass the probable

mzxirnum flood. For s~nd dams, spill-

ways are designed to pass a standard project flood. Detailed procedures and com-

puter programs for these types of analyses are available from the U.S. Army Corps

of Engineers

971).

Recently states have unplen~ented federal dam safety regula-

tions which

must be met in any developments that involve dams over a minimum

height of

ft. Normally each state's dam safety

regulations

sllould be referred to

making spillway flood determinations. Another good reference is the "Manual of

Standards and Criteria for Planning Water Resources Projects" (United Nations,

1964).

REFERENCES

Buchanan,

J.,

and W. P. Somers, "Discharge Measurements at Gaging Stations,"

Chapter

Techniql~es of Water Resource Investigatiol~s of the U.S. Geological

Sfrrvey,

Book

Applications of Hydraulics.

Washington, D.C.: U.S. Department

of the Interior, 1969.

Chankong,

V.,

and

D. D.

hieredith, "Optimal Operating Rules for Reservoirs: Pre-

limi11ar)~ Formulation and Procedures,"

Iflater Resource and El~viror~mental

Enpir~cerir~g Research Report 79-5.

Buffalo, hl.Y.: Department of Civil Engineer-

ing. State University of New York, 1979.

Chap.

References

Crawford, N.

H.,

and

Linsley, "Digital Simulation in Hydrology: Stanford

Watershed Model Mark IV,"

Civil Engineering Tecl~nical Report 39.

Stanford,

Calif.: Stanford University, 1966.

Emn~ert,

L.,

"Methodologies for the Determination of Flow Duration Curve3

Specific

Sites

Ungaged Reaches

Str~nrne."

lJr~~~~~l,lislr~rl

flfnoh,

Ilc(,nt~

ment of

Civil

Engineering, Univemlly

Iii:~l~o, Muncr~w, I~ILIIIc),

I1)1'J.

Gladwell,

S.,

Heitz, and C.

Warnick, "Phase

Resource Survey of

Low-Head Hydroelectric Potential-Pacific Northwest Region,"

Completion

Report to

U.S.

Departlnent of Energy,

Idaho Water Resources Research Institute,

University of Idaho, Moscow, Idaho, March 1978.

Haan, C.

T.,

Statistical Methods in Hydrology,

Ames, Iowa: Iowa State University

Press, 1977.

Heitz,

F.,

"Some Hydrologic Analysis Techniques."

Low-Head Hydro.

Gladwell and C. C. Warnick, eds. Moscow, Idaho: Idaho Water Resources Research

Institute, University of Idaho, 1 978.

"Hydrologic Evaluation Methods for Hydropower Studies." Unpublished

Ph.D. dissertation, Department of Civil Engineering, University of Idaho, Mos-

cow, Idaho, 1981.

and R.

Emmert, "Determination of Flow-Duration Curves at Ungaged

Points on Regulated Streams,"

Conference Proceedings, Waterpower

'79:

The

First International Conference on Small-Scale Hydropower.

Washington, D.C.:

U.S. Government Printing Office,

1979.

Linsley, R.

K.,

A. Kohler, and

Paulhus.

Hydrology for Engineers.

New

York:

McGraw-Hill Book Company, 1975.

Searcy,

K.,

"Flow Duration Curves." In

Manual of Hydrology,

Part

Low Flow

Techniques, Geological Survey Water Supply Paper

1542.

Washington, D.C.: U.S.

Department of the Interior, 1959.

United Nations, "Manual of Standards and Criteria for

Planning Water Resources

Projects,"

Water Resources Series No.

26.

New York: United Nations, 1964.

U.S. Army Corps of Engineers,

Hydrologic Engineering Methods for Water Re-

sources Development,

Vol. 1

Requirements and General Procedures.

Davis, Calif.:

The Hydrologic Engineering Center, U.S. Army Corps of Engineers, 1971.

U.S. Army Corps of Engineers, "Program Description and User

Manual for SSAR,

Streamflow Synthesis and Reservoir Regulation,"

Program

724-K5-GOOIO.

Port-

land, Oreg.: U.S. Army Corps of Engineers, North Pacific Division, 1972.

U.S. Army Corps of Engineers,

Hydrologic Engineering Methods for Water Re-

sources Development,

Vol. 9:

Reservoir Systems Analysis and Conservation.

Davis, Calif.: The Hydrologic Engineering Center, U.S. Army Corps of Engineers,

1977.

U.S. Army Corps of Engineers,

Nationol Hydropower Study.

Ft. Belvoir, Va.: Water

Resources Institute, U.S. Army Corps of Engineers, 1980.

U.S. Water Resources Council, "Guidelines for Determining Flood Frequency,"

Bulletin No. 17A.

Hydrology Committee. Washington, D.C.: U.S. Water Resources

Council, 1977.

Veihmeyer,

J.,

"Evapotranspiration." In

Handbook of Applied Hydrology.

V. T.

Chow, ed. New York:

McGraw-Hill Book Company, 1964.

Hydrologic

Analysis

for Hydropower Chap.

Viessrnan,

W.,

Harbaugl~, and

Knapp,

lrltroduction

Hydrology.

New

York:

lntzxt Educationnl Publishers, 1972.

World Meteorological Organization, "Guide to Hydrometeorological Practices,"

1V1\10

No.

168,

2nd ed. Geneva: Secretariat of the World Meteorological Organi-

zation, 1970.

PROBLEMS

5.1.

Generate from actual flow data a flow duration cume forusein hydropower

computations using a historical record of at least 10 years'length. Compare

flow duration study done with daily flow values with one done with monthly

flow values.

5.2.

drainage basin in the Little Salmon River has a possible hydropower site

that is not near a stream gage (see Fig. 5.15). Planimetering of the areas

between

isohyetal lines provides the data given in Table 5.3. The runoff coef-

ficient for

the proposed site is estimated to be 0.64. The equations for the

parametric flow duration curves similar to Fig. 5.4 that apply to the Little

Salmon River basin have the following regression equations for determining

the

flotvs at five exceedance percentages:

log

Q,,

0.534

0.965 log

log Q,,

-0.299

1.049 log

log

Q,,

-0.574

1.084

log

Q8,

-0.754

1.101 log

logQgS

=-0.853

1.107logg

where

in [(ft3/sec)(day)] units and

is in ft3/sec. Develop a duration

curve for power

st~rdies at the point marked on the map of Fig.

5.15.

5.3.

drainage basin in the Payette River basin has a power site designated at the

mouth of Deadwood River (see Fig. 5.16). The Deadwood Reservoir used for

irrigation regclates the flow of the upper portions of the drainage. The area of

the hydrologic map representative of the drainage basin contributing flow at

the mouth has

been planirnetered and Table 5.4 gives the information needed

to compute average annual precipitation input to the basin below the reser-

voir.

runoff coefficient for the bssin on the annual basis is

0.65. The

llisroric monthly flows of a nearby stream gage on the South Fork of the

Payette River are presented in Table 5.5, The gage records are considered to

good representation of seasonal variation of runoff for the ungaged

portion of

tl~e Dcadwootl River drainage. Using techniques discussed in this

chapter, develop a flow duration curve for the flow at the mouth of the Dead-

wood

Rivcr that would be useful in hydropower studies.

5.4.

Obtain a sequential-flow reservoir operation or runoff model and study it for

possible application in a hydropower study.

Chap.

Problems

Riggins stream

gage

miles

Scale

Figure

5.15

Normal-annual-precipitation map of Little Salmon River Basin, Idaho.

Figure

5.16

Hydrologic map of Deadwood River Basin. Idaho.

Chap.

Problems

TABLE

5.3

Vall~es of Planimetered Areas from the Normal

Annual Precipitation Map of Drainagc Basins in tl~e Little

Salmon River System

~vera~e Value of Precipitation Planimetered Arm

between Isohyetal Lines (in.)

(inO2)

Elk Creek

2 5 0.20

3 5 0.57

40 0.33

Hazard Creek

20 0.11

25 1.35

5 2.38

4 0 0.44

4 5

0.81

50 0.11

Proposed Site (near Fall Creek)

20 0.65

25 6.40

30 0.41

3 5 14.14

40 1.02

45 1.16

50 0.10

TADLE

5.4

Values of Planimetered Areas from the Normal

Annual Precipitation Map of Drainage Basins

the

Payette River System

Average Value of Precipitation

Planimetered Area

between Isohyetal

Linrc (in.) (in2)

Entire Deadwood River above the Mouth

30 2.3

3 5 859

4 0 2.81

45 1.02

55 0.49

0 0.05

Area below Deadwood Reservoir

1.85

35 4.05

4 0 2.24

Hydrologic Analysis

for

Hydropower

Chap.

TABLE

5.5

hlonthly Flows for an Average Year

a Gaged Stream of the Payette River System

Month

Discharge

(ft

3/sec)

October

November

December

January

February

March

April

May

June

July

August

Sep

tern

ber

TURBINE

SELECTION

AND

PLANT'

CRPBCBTV

DETERMINATION

BASIC PROCEDURES

Turbine selection and plant capacity determination require that rather detailed

information has been determined on head and possible plant discharge as described

earlier. In practice, different selection procedures are used. Engineering

fms or

agency engineering staff do the selection using experience curves based on data

from units that have already been built and

installed or tested

laboratories. An

excellent description of one governmental agency's approach is

Engineering

Mono

graph

No.

of the

U.S.

Department of the Interior

976).

Another approach that

is preferred by manufacturers is that they be provided with the basic data on head,

water discharge, turbine setting possibilities, and load charactersitics. The selection

then based on

hill

curves from model performance data that are

proprietary

nature. Normally, the manufacturers provide a checklist similar to Table

6.1

which

is the basis for making the selection.

The

manufacturer furnishes preliminary esti-

mates of the cost of the turbines and necessary mechanical equipment and controls,

together with basic characteristics and

dinlensions of the hydropower units.

theoretical sense, the energy output,

can be expressed mathematically

as plant output or annual energy in a functional relation as follows:

F(h,

TW,

Hs,

P,,,)

(6.1)

where

net effective head

plant discharge

tailwater elevation

diameter of runner

Turbine Selection and Plant Capacity Determination

Chap.

TABLE 6.1

Typical Checklist of

Selection Inforniation Required

hlanufacturers

INFORhlATlON REQUIRED

ALLIS-CHALMERS CORPORATION

FOR

THE APPLICATION AND SELECTION

OF'

HYDRAULIC 'TURBINES

Our complete facilities are at

tlie service of water power users. \Ve provide recommendations,

layou is, and proposals for both new dcvelopments and the

reconstructing

of existing plants.

However, proper selection and application requires specific,

dctailed information. To prepare

complete proposal promptly, it is importulit that the following data, where applicable and

availalole. be sent with each inquiry.

Name of firm or corporation, with address.

Location and name of plant.

Approximate elevation of the plant above sea level.

Total quantity of water in cubic feet or cubic meters per second, with comments regard-

ing the variations in daily and seasonal flow as well as storage capacity; flow duration

curves; and drainage area.

Quality of the water. Does it contain sand, chemicals, or other impurities?

Gross head (vertical distance from the headwater level to the tailwater level), with any

known variations, preferably correlated with flow.

If already determined, net or effective head on which all guarantees are to be based, with

any known variations. (If it has not been determined, we are prepared to estimate the

net effective head based on tlie penstock or flume dimensions.)

Amount of power desired or required.

Dischargr or load at which maximum efficiency is desired.

10.

Number and size of the units contemplated or required now and for future installation.

If new

unlts are to be sized for an existing plant, give space limitations and de:ails of

existing foundations and superstructure.

11.

Distance from normal tailwater level to powerhouse floor, with variations and relation

to flow.

12.

Proposed length, diameter, and material of the supply pipe (penstock) if required.

aiready designed or installed, givc complete information.

13.

If a surge tank is installed or contemplated on the pipeline, the distance along the pen-

stock from the surge tank to the powerhouse and all available surge tank data.

14.

\\ill the plant operate separately or in parallel with a power system? If in parallel, give

the

approximate installed capacity of the system and its frequency.

15.

hlethod of intended operation-manual, selniautornatic, fully automatic, or remote

control.

16.

Supplementary information with drawings or sketches, to assist in proper interpretation

the data.

Since

many dimensions may be changed before the plant is actually constructed, the purchaser

must be responsible for the net effective

Iiead, the elevations of thc head and tailwater levels,

and the quantity of water, as

well as the exactness of all iield information on which the final

design of

the turbines is based.

SOURCE:

Allis-Chalmers Corporation.

Baslc Procedures

generator speed

turbine setting elevation above tailwater

Pma,

maximum output expected or desired at plant.

is seen that there are numerous parameters that can be varied

achieve the best

selection. The usual practice is to base selection on the annual energy output of

the

plant and the least cost of that energy for the particular scale of hydropower

installation. Thus one must recognize that determination of plant capacity requires

analyses that vary the different parameters in

Eq.

(6.1)

while applying economic

analyses.

For

preliminary planning it is sometimes useful to get an order-of-magnitude

estimate of the unit (or units) capacity and cost to be expected.

curve

(Fig.

6.1)

prepared by consulting engineers

Tippetts-Abbett-McCarthy-Stratton

is useful in

making such trial evaluations. If the energy costs exceed60

mills;kR11(1981 prices),

the economics of the development

will

be marginal. The curves presented are for

conditions of water flow and yield of rivers in the northeastern United States.

similar type of nomograph for sizing standard

TUBE

units is presented in

Fig.

6.2.

This

gives an idea of the range of unit sizes that can be cons~dered at a

particular site. Another useful reference is an engineering manual by the

U.S.

Army

Corps

Engineers

952).

Figure

4.4

is a useful selection chart for determining the type of unit at the

Drainage area In square miles

Figure

6.1

Nomograph for determining installed capacity. SOURCE: O'Brien.

TAMS.